atom/themes/atom-light-ui/editor.css

.editor {
  font-family: Inconsolata, Monaco, Courier;
  line-height: 1.3;
}

.editor.mini {
  height: auto;
  line-height: 25px;
  border: 1px solid rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid rgba(180, 180, 180, 0.3);
  border-right: 1px solid rgba(180, 180, 180, 0.3);
  background-color: #aaa;
  color: #333;
}

.editor.mini .cursor {
  background: #333;
  width: 2px;
  line-height: 20px;
  margin-top: 2px;
}

.editor .gutter .line-number {
  padding-right: .5em;
  min-width: 35px;
  box-sizing: border-box;
  text-align: right;
  opacity: 0.5;
}

.editor .gutter .line-number.cursor-line {
  opacity: 1;
}

.editor .gutter.drop-shadow {
  -webkit-box-shadow: -2px 0px 10px 2px #222;
}

@-webkit-keyframes highlight {
  from { background-color: rgba(100, 255, 100, 0.7); }
  to { background-color: null; }
}

.editor .highlighted.selection .region {
  -webkit-animation-name: highlight;
  -webkit-animation-duration: 1s;
  -webkit-animation-iteration-count: 1;
}

.editor .gutter .line-number.fold {
  color: #fba0e3;
  opacity: .8;
}

.editor .gutter .line-number.fold.cursor-line {
  opacity: 1;
}

.editor .gutter .line-number:after {
  font-size: 0.8em;
  content: '\f078';
  font-family: 'Octicons Regular';
  -webkit-font-smoothing: antialiased;
  color: #fba0e3;
  visibility: hidden;
}

.editor .gutter .line-number.fold:after {
  visibility: visible;
}

.editor .fold-marker:after {
  content: '\2026';
  opacity: .8;
  color: #fba0e3;
  padding-left: .2em;
}

.editor .line.cursor-line .fold-marker {
  opacity: 1;
}

.editor .invisible {
  opacity: 0.2;
}